1. Field of the Invention
The present invention relates generally to amphibious vehicles, that is, vehicles adapted to move on land and on water.
2. Background of the Invention
Amphibious vehicles are primarily known for their use in military operations, such as use in a beach assault or river crossing. These vehicles are highly specialized for carrying soldiers and materials in special circumstances. Commercial use of amphibious vehicles is also known. For example, an amphibious vehicle may be used for tours that take place primarily on water but may include a short drive on land.
Designing a vehicle that can operate on land and on water has obvious advantages but also requires the designer to overcome significant obstacles. For example, the propulsion system for operation on land and on water must be capable of meeting very different requirements. Driving on the road requires the capability to reach higher speeds and to overcome wind resistance and static and rolling friction of the wheels. Driving on water requires the propulsion system to operate at much lower speeds, to overcome water resistance, and to cope with the buffeting effect of water on the bow. Buoyancy and stability in the water, particularly in water that is not calm, is an additional important factor in the design of an amphibious vehicle. Finally, stability in operating at highway speeds or in cornering versus stability in the water impose very different constraints.
Less obvious than the different physical requirements the vehicles must meet are the different legal requirements that apply to vehicles that move on the highway versus those that move in the water, especially vehicles designed for hauling passengers. These legal requirements include such matters as the type of driver""s license required for operation of the vehicle and special permits for wider or heavier vehicles.
Nonetheless, if a particular design is at least able to overcome the physical requirements, it can perform useful functions, not just in military applications but in commercial and other applications as well. For example, amphibious vehicles can be of significant importance in search and rescue operations following flooding of low-lying areas, and in traveling to areas where neither the roads nor the waterways lead everywhere, such as, for example, island chains separated by distances too great for bridges.
Various attempts have been made to design a suitable amphibious vehicle. For example, there is the amphibious vehicle described by Caserta et al., in U.S. Pat. No. 5,727,494. Their amphibian has the drive train mounted on top of two or three pontoons. It also has four retractable wheels powered from the rear of the vessel.
Another amphibious vehicle design is taught by Wardavoir, U.S. Pat. No. 5,410,980. Wardavoir describes the prior art approaches to designing an amphibious vehicle: adding a boat hull to a conventional motor vehicle and adding a terrestrial transmission to a conventional boat. His design focuses on producing a chassis that overcomes problems with these two prior art approaches, namely, by providing sufficient rigidity for land use yet being sufficiently light and balanced for use on water.
However, there remains a need for an amphibious vehicle that performs satisfactorily on land and on water.
According to its major aspects and briefly recited, the present invention is a vehicle capable of operation on a waterway and on a highway. In particular, the present invention is an amphibious vehicle having a hull mounted to components of a medium or heavy duty truck in such a way that the drive train of the truck is interior to the hull but the wheels, axles, breaks and suspension system of the vehicle are exterior to the hull. The hull has a channel or xe2x80x9cpodxe2x80x9d formed in it running parallel to and centered on the long dimension of the hull. The pod is dimensioned to receive the drive train including the radiator and, because of the location of the pod with respect to the balance of the hull, and the impact of placing the drive train in there on the center of gravity of the vehicle, it greatly improves the stability of the vehicle in water. The balance of the hull, located on either side of the pod and at a relatively higher elevation, is divided into sections and filled with foam.
A feature of the present invention is the shape of the hull in combination with the location of the drive train in it. Locating the drive train in the lowest part of the hull, indeed, in a pod below the balance of the hull, uses it as ballast for the hull. The shape of the hull with its pod, combined with the weight of the drive train, also allows it to act in a manner similar to that of the keel of a sailboat. With this arrangement, the vehicle is more stable in the water and on the road.
The combination of the pod and the foam-filled sides of the hull creates a boat that is unsinkable and even more stable in the event the engine compartment becomes flooded. The foam-filled sections flanking the pod are the equivalent of a pair of matched pontoons that, because of the existence of the foam, will not ship water even if the hull is breached. Because of the weight of the drive train, the pod rights itself no matter what forces are applied to capsize the hull.
Locating the drive train in the pod is another feature of the present invention because it makes it much easier to service and repair or replace the drive train. Furthermore, the shape and location of the pod allows both easier replacement of the drive train and the use of different truck engines.
These and other features and their advantages will become apparent to those skilled in hull design from a careful reading of the Detailed Description of Preferred Embodiments, accompanied by the following drawings.